The present invention relates to an optical navigation system for use in applications requiring accurate positioning of a toolpiece in relation to a workpiece. More particularly, the present invention relates to an optical navigation system for positioning a toolpiece in accordance with a known navigation surface.
In devices which perform operations on a workpiece, it is often necessary to accurately position a toolpiece in relation to the workpiece in order to carryout the desired operations so as to achieve desired results. In operations wherein repeatability is important, the need to accurately control the position of the toolpiece throughout each successive interaction of the operation in relation to the workpiece is very important.
One example of a device that performs operations on a workpiece is a typical printing device, for example, but not limited to, a laser, ink jet, or dye-sublimation printer or the like is shown in FIG. 1. FIG. 1 shows a printer cartridge 30, a storage reservoir 35, a print head 33, and a print media 31. These printers perform printing operations by distributing a dye, or pigment, onto a print media such as paper or resin coated substrate.
During the printing process carried out by a typical printing device it is common to move the print head about the surface of a print media in order to deliver pigment, or dyes, to the print media at predetermined locations thereon. In order to achieve desired and repeatably consistent results, it is necessary for the positioning of the printer head to be accurately controlled.
Known methods of controlling the positioning of the printer head include the use of rotary shaft encoders that monitor the rotation of shafts which feed the print media through the printing device during the printing process, glass etched optical encoders, as well as stepper motors. Unfortunately rotary encoders suffer from mechanical backlash which precludes consist and accurate control of print head navigation. Glass etched encoders are very expensive and not useful in cost sensitive applications where high resolution printing is desired. Finally, stepper motors suffer from inaccuracies due to loss of step count. Additionally, stepper motors are relatively expensive.
Optical navigation systems have been employed to determine the position of a toolpiece in relation to a work piece, however, because these systems have relied upon a the surface or feature of the print media itself, there were inconsistencies in results. Thus, a heretofore unaddressed need exists in the industry to address the aforementioned deficiencies and inadequacies.
The present invention provides for a cooperative navigation surface, a navigation unit for optically monitoring the navigation surface, and a navigation engine for generating an output signal representative of the position of a toolpiece. The present invention provides for navigation of a print head for printing onto a print media based upon optical feedback derived from a known cooperative navigation surface, while printing onto a separate independent surface, or print media. Further, the present invention seeks to provide a navigation unit which tracks movement of the print head in the X direction and movement of the print media in the Y direction. By providing for optical navigation of a known navigation surface, the present invention seeks to avoid errors and inaccuracies that are common with typical optical navigation systems.
The present invention can also be viewed as providing a method for printing on a print media. In this regard, the method can be broadly summarized by the following steps: optically monitoring a cooperative navigation surface and generating an image output signal in accordance therewith; and delivering a pigment to a print media in accordance with said image output signal.